Help with Date Range query

Actual SQL noob, but trying to get a query to work inside MS Access. (Low end database for work but I'm constrained by what the organisation allows for department level applications and don't have project approval for outside help to build something bespoke)
Two Tables:
tbl_Vacancy (Fields: VacancyID, VacancyStart, VacanacyEnd)
tbl_SAForms (Fields: SAFID, SAFVacancy(Relates to VacancyID), SAFStart, SAFEnd)

Vacancy is the entire period of a staff absence
SAForms (Staff Action Forms) are fulfillment of those vacanacies (in part or full)

I need a query that will show the unfilled periods for vacancies listed in tbl_Vacancy which are not covered by an entry in tbl_SAForms.

I can show you the code I've got so far - but to be honest its outside my comfort zone, majority written by CHAT-GPT and getting missing operator errors - so doesnt work.

Hope that's not too much help to ask for.